Spray polyurethane foams are formed by combining a polyol component and a polyisocyanate component in the presence of a blowing agent. Polyether polyols are often used in the polyol component. Such polyether polyols are typically made by reacting a polyol with an alkylene oxide in the presence of an alkaline catalyst.
In some cases, a raw, natural-occurring polyol, such as raw sucrose, has been included in the polyol component of a spray polyurethane foam formulation, since raw sucrose can “char” upon burning, thereby acting as a flame retardant. However, the use of large quantities of a raw, naturally-occurring polyol, such as raw sucrose, for this purpose can pose several problems. First, the raw naturally-occurring polyol, such as raw sucrose, in the polyol component of the formulation can precipitate and deposit in shipping containers as well as process equipment, thereby causing equipment damage during the spray application process. Such precipitation can also affect the stoichiometry of the resulting polyurethane spray system, resulting in poor reactivity and foam performance properties. To compensate for poor reactivity, over-catalysis through the use of high amount of an amine catalyst is possible, but this can be undesirable. Thus, it would be desirable to reduce the amount of, or even eliminate, raw sucrose used in such formulations.
Standards for flame spread of spray-applied foam plastic insulation are set forth in International Code Council Evaluation Service (“ICC-ES”) Acceptance Criteria (“AC”) 377, Appendix X. Currently, to meet the requirements of ICC-ES 377, Appendix X, spray polyurethane foams typically require the application of an ignition barrier over the foam. This ignition barrier can be, for example, ¼″ thick plywood or an intumescent coating. The need to apply an ignition barrier over the polyurethane foam is undesirable from, for example, a material cost and labor cost standpoint.
It would be desirable to provide a polyether polyol composition that can be used as part of a spray polyurethane foam formulation that produces a foam that passes the requirements of ICC-ES AC377, Appendix X in the absence of the presence of an ignition barrier applied over the foam and which is less dependent on or, in some cases, completely eliminates, the use of a raw, naturally-occurring polyol, such as raw sucrose, in the spray polyurethane foam formulation to achieve sufficient fire retardency.